Dick has it right on. The clean airframe helps a lot in cruise and fuel burn. It's hard to overcome weight in climb out especially since that's when the plane is the heaviest. You look to be on a very good track. Does it have to R.O.G. to leave the ground or is there another way it can launch? Think about possible benefits with something other than an ROG T/O.

Sorry, but I have to leave this one now.